Microporous polyolefin membrane and method of producing same
First Claim
1. A microporous polyolefin membrane made of a polyolefin composition comprising 1 to 90 weight % per 100 weight % of the polyolefin composition of an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 7×
- 105 or more and a polyolefin having a weight-average molecular weight of between 1×
104 to less than 7×
105, said polyolefin composition having a weight-average molecular weight/number-average molecular weight ratio of 10-300, said microporous membrane having a thickness of 0.1-25 μ
m, a porosity of 35-95%, an average pore diameter of 0.001-0.02 μ
m and a breaking strength of 0.2 kg or more per 15 mm width.
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Abstract
A microporous polyolefin membrane made of a polyolefin composition containing 1 weight % or more of an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 7×105 or more and having a weight-average molecular weight/number-average molecular weight ratio of 10-300, the microporous membrane having a thickness of 0.1-25 μm, a porosity of 35-95%, an average pore diameter of 0.001-0.2 μm and a breaking strength of 0.2 kg or more per 15 mm width is produced by (a) preparing a solution comprising 10-50 weight % of the polyolefin composition and 50-90 weight % of a solvent; (b) extruding the solution through a die; (c) cooling the extruded solution to form a gel-like article; (d) stretching the gel-like article at a temperature equal to or lower than a melting point of the polyolefin composition +10° C; and (e) removing the remaining solvent.
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Citations
10 Claims
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1. A microporous polyolefin membrane made of a polyolefin composition comprising 1 to 90 weight % per 100 weight % of the polyolefin composition of an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 7×
- 105 or more and a polyolefin having a weight-average molecular weight of between 1×
104 to less than 7×
105, said polyolefin composition having a weight-average molecular weight/number-average molecular weight ratio of 10-300, said microporous membrane having a thickness of 0.1-25 μ
m, a porosity of 35-95%, an average pore diameter of 0.001-0.02 μ
m and a breaking strength of 0.2 kg or more per 15 mm width. - View Dependent Claims (2)
- 105 or more and a polyolefin having a weight-average molecular weight of between 1×
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3. A method of producing a microporous polyolefin membrane comprising the steps of:
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(a) preparing a solution comprising 10-50 weight % of a polyolefin composition comprising 1 to 90 weight % per 100 weight % of the polyolefin composition of an ultra-high-molecular-weight polyolefin having a weight-average molecular weight of 7×
105 or more and a polyolefin having a weight-average molecular weight of between 1×
104 to less than 7×
105, said polyolefin composition having a weight-average molecular weight/number average molecular weight ratio of 10-300, and 50-90 weight % of a solvent;(b) extruding said solution through a die; (c) cooling said extruded solution to form a gel-like article; (d) stretching said gel-like article at a temperature equal to or lower than a melting point of said polyolefin composition+10°
C.; and(e) removing the remaining solvent. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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Specification